Instrumentation and monitoring: Delivering data diagnostics

Modern monitoring equipment can generate a multitude of data although understanding the results in a realistic timeframe can be challenging. GE takes a look at some new software that could ease this problem to make this data more powerful than ever.

The move to real-time geotechnical and structural monitoring was hailed as an essential step forward in managing ground movements related to ever more complex and deeper excavations but the reality for many if quite different. The result of this step-change in equipment on site is large spreadsheets that struggle to cope with the volume of data and call for intensive user manipulation to get the best interpretation.

This was an issue that Geotechnical Observations managing director Andrew Ridley was dealing with himself in helping his customers to understand their monitoring results and led him to look for an alternative. After two years of development, his company is ready to launch Geodaisy which is a software solution that he believes puts effective and efficient interpretation of monitoring data into the hands of the user.

According to Ridley, Geodaisy firmly takes his business back to its origins. “When we established the company in 2000 , the aim was to help the sector gain greater understanding of monitoring data.

Our strapline was monitoring, testing and understanding,” says Ridley. “We felt that it was the understanding element of our business that differentiated us from other players in the market.

“We used to produce interpretive reports for customers but now data is presented through web-based systems and these don’t offer interpretation. Instead engineers are downloading the data and using spreadsheets to analyse it graphically.”

The amount of data that modern monitoring generates means that this is an onerous task. Ridley says that a single Shape Array could generate more than 2M readings in the space of a year and projects often have a number of these instruments on any one site.

“The amount of data lends itself to a database but engineers like to play with data so use spreadsheets,” explains Ridley. “Spreadsheets used to analyse data on this scale end up being huge and often crash before the analysis has been completed.”

Geodaisy, which stands for Geotechnical Observations’ Data Analysis and Interpretation System, aims to solve that by including interpretive tools and allowing engineers to play with the data without upsetting the underlying database.

Ridley says that the software has the power of a database but the ease of a spreadsheet and is all available online.

“The system allows users to create their own graphs and these are updated whenever new data becomes available,” says Ridley. Under the conventional approach, users would have to download data and manually add it to the spreadsheet before regenerating graphs for analysis.

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The map function allows engineers to draw sections

Ridley says the software is designed to work in a similar way to what people do when they analyse data and provides customers with what they need to make better and more informed decisions based on the most up to date data.

With Geodaisy users no longer have to download the data but they still have the option to do so, if they want to.

Ridley says that the system has all the tools you would expect with a spreadsheet, including curve fitting, annotation and the ability to change everything about a graph.

“Each user has their own unique profile and they can store their own graphs and see graphs created by other users within the same company or project, so that they can share information,” he explains. “There is also the option to make analyses private, should a user wish to do so.

Geodaisy is more than just a monitoring database though – it also allows users to store documents such as the monitoring specifications, sensor calibration sheets and installation records, contact details for people working on the project and photographs.

“Having a photographic record of the same position that is time-stamped can help with understanding monitoring results,” says Ridley. “It can be difficult obtaining accurate information on the progress of construction by word of mouth.”

Ridley points to one contract where displacements recorded were much higher than expected and photographs helped the team establish the progress of construction at the time of the measurements and verify that the readings were consistent with the sequence of events.

The basis of the Geodaisy system is a GIS map which marks out the site, the sensor positions and photograph locations and can also be annotated.

“One of the things that is often missed in monitoring is the resultant movement,” says Ridley. “People often talk about the movement in the x and y direction but it is usually the resultant movement that is critical. Alarm thresholds of 10mm are not unusual these days. Monitoring results may show less than this in the x direction but a small amount of movement in the y direction could cause the resultant displacement to exceed the threshold and trigger an alarm.

“Geodaisy simplifies the process to understand this resultant movement and displays it more visually.”

In the future, Ridley says the vectors will automatically appear on the maps if required.

The map function also allows the user to draw a section through the site, which Ridley says is particularly useful for slope monitoring applications. There is a contouring function, which helps users to interpret settlement and heave processes.

These are all tasks that Geotechnical Observation’s customers have been undertaking themselves but through the use of spreadsheets and Ridley says that Geodaisy will speed up the interpretation.

Geodaisy also allows alarms to be set and adjusted according to the movement recorded, as well as set using the curve fitting function to minimise false alarms caused by noisy data. If the system does trigger an alarm, it not only alerts users but also creates a process that ensures the team undertake checks to understand why the alarm was triggered. Also, if the movement hovers around the alarm level and then increases or decreases the system will warn the project team and can predict when the next threshold will be breached. Such predictions are automatically updated based on the system’s knowledge of the data it receives. Ridley thinks this is a major benefit as many existing systems only trigger an alarm once the threshold is reached and do not offer further alerts until another threshold is breached.

Despite the automation Geodaisy offers, Ridley says that users still need to have geotechnical knowledge to use the system and understand the interpretation of the results. His vision though is to bridge the gap between monitoring specialists providing data and engineers making decisions.

In the time it has taken to bring the software to launch, the system has evolved considerably. “I originally envisaged it as an alternative to our current methods of data presentation but it has evolved to become as much about the interpretation,” says Ridley. “It is now an analytical tool as well as a way of getting our monitoring data to our customers.”

The software will become commercially available to Geotechnical Observation’s clients this autumn but Ridley is already working on the next stages of development and has a number of ideas to further improve functionality. One of the main developments will be an app to allow engineers on site to add as-built data to the system.

Nonetheless, Ridley says he wants customers to start using the system and provide feedback to also aid the development process. He hopes that the greater analytical power will give engineers better understanding and more confidence in monitoring data.

New monitoring technology which combines geophysical ground imaging technology and web-based data visualisation with intelligent monitoring adds an important tool for geotechnical engineers, according to the British Geological Survey (BGS) which led development.

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